从约束试验提取阻尼自由结构主模态

Extraction of normal modes of damping free structure from constrained test data

对于大型自由结构,如大型运载器,要实现自由状态下的模态试验是愈来愈困难了。为此,人们被迫只好对这类结构进行约束状态下的模态试验。这样就要求从约束状态试验所测得的数据中提取到原自由状态下的试验模态参数。本文针对这个问题提出了一种“提取方法”。数值模拟结果表明,该方法的精度相当满意,不论是无阻尼,还是考虑有阻尼的情况,都可以获得工程上满意的结果。

For large scale free structure with very great weight, such as a large and heavy-duty launch-vehicle, the free-free modal test is realized difficultly. For this reason, one is compelled to make constrained test of the large launch-vehicle(free structure). Thus it is required to extract normal modes of damping free structure from constrained test data. When the structure is undamping, the method developed in this paper can identify the usual real eigenmodes. Numerical simulation results show that precision of the present method is satisfactory.